Computer networks provide for data communications between data processing equipment. For example, data processing devices such as portable lap-top computers, desk-top personal computers, file servers, mini-computers, mainframe computers, printers, and the like can be interconnected using a computer network to advantageously share programs, data, and other information resources.
Devices located in a proximate area are interconnected to one another on the same network sub-net. Remotely located devices are interconnected to one another on a different network subnet, however devices located in proximate and remote areas can be connected by connecting the network subnets.
An example of a popular computer network is generally known as an "Ethernet" local area network, or as specified by the International Standards Organization in ISO 8802/3. Ethernet advantageously provides fast data transmission rates of 10 Megabits per second, and can be extended to 100 Megabits per second or more.
For network communication, each device is mechanically and electrically connected to the computer network at a respective tap point of the network. Each tap point of the network is identified by a respective computer network address. The computer network addresses are used in transmitting data between devices connected to the network.
Data is transmitted over the computer network in formatted data packets, each comprising, for example, an ordered arrangement of a preamble 101, a start-of-frame indicator 103, a destination address segment 105 for indicating the computer network address of a tap point of the network for receiving data, a source address segment 107 for indicating the computer network address of a tap point of the network for transmitting data, an information length segment 107, an information segment 111, and a frame check segment 113, as shown for example in FIG. 1. Other alternative ordered arrangements of segments within the complete data frame are also known to those skilled in the art. The computer network addresses are used by switching equipment of the network to control routing of the data packets.
For typical network use, each device connected to the network must have a register entry of the respective computer network address (which is called an "IP Address", IP standing for Internet Protocol) for identifying the respective tap point of the network. For example, for typical network use of a portable lap-top computer in a particular office, the portable lap-top computer must have a register entry of a first computer network address for identifying a predetermined tap point of the local network. If the portable lap-top computer is disconnected from the network, moved, and then reconnected elsewhere, for example for use in a remote conference room, reconfiguration is needed to change the register entry, so that the portable lap-top computer has a register entry of a second computer network address for identifying a second tap point of the network. Such reconfiguration is again required upon returning to the previous location, and once again for network use in each subsequent remote location. Performing such reconfiguration manually is a burdensome task and is prone to errors, especially for a typical computer user of business application programs, who is lacking in that particular technical skill.
Even if such reconfiguration is correctly effected, other limitations still remain. Typically network security systems, firewalls, access control schemes, network file system (NFS), and the like limit access based upon computer network addresses and tap points of the network. Accordingly, a hypothetical network security system allows network access to important files on a file server using the portable lap-top computer in the particular office, because the network security system recognizes the first tap point of the network, and also recognizes the first computer network address that identifies the first tap point of the network. However if that portable lap-top computer is disconnected from the network, moved, reconnected elsewhere, such as in the remote conference room, and then reconfigured as discussed previously herein, the network security systems refuse to allow access to the important files on the file server. This is because the network security system does not recognize the second tap point of the network, and does not recognize the second computer network address that identifies the second tap point of the network.
So called "wire-less modems", cellular telephone modems, and the like provide some advantages, but there are also limitations. For wire-less modems, data rates are not as high as are as those achieved, for example using Ethernet, with a device that is mechanical and electrically connected to the computer network at the tap point of the network. For wire-less modems, different broadcast standards and schemes in different counties prevent convenient universal operation, while hard-wired network connections, for example Ethernet connections, are advantageously operating all over the world. Furthermore, wire-less modems pose greater security risks, since wire-less data transmissions are more easily intercepted than with hard-wired network connections, such as Ethernet connections.
What is needed is an apparatus and method for computer network configuration and address mapping to provide convenient, secure, and flexible high speed communication between devices on the computer network.